This patent relates to x-ray detectors, and more specifically to x-ray detectors fabricated from crystalline silicon such as complementary metal-oxide-semiconductor (CMOS).
In recent years, medical imaging has demonstrated an increasing interest in the use of crystalline silicon-based x-ray detector panels, which are light image sensors having a two-dimensional photodiode array of sensing pixels typically fabricated on crystalline silicon using CMOS technology. Such light image sensors have been demonstrated to outperform the traditional amorphous silicon-based x-ray detector in low dose fluoroscopic products, such as mobile c-arm devices commonly used in surgical settings. In these devices, an object to be imaged is place between an x-ray generator, or x-ray tube, and an image sensor. X-rays are projected at the object, and an x-ray attenuation image containing information about the internal structure of the object is projected onto the x-ray detector. The image represents the x-ray absorption properties of different parts of the object. In the x-ray detector, the x-ray photons are converted to visible light in a scintillator layer. The visible light, in turn, is absorbed into the silicon in the sensing pixels of the light image sensor, where the photons turn into electrons and the electrons are stored in one or more capacitors. The number of electrons in each pixel is proportional to the intensity of light projected onto that pixel. During the readout phase, the number of electrons stored in the capacitor or capacitors associated with each pixel is sampled and then transmitted sequentially to the readout electronics.